Confining ingested fluid to the stomach increases water and decreases saline intake in the rat [corrected].

Rats ingest more pure water in a 30-min test following 17 h of water deprivation when the ingested water is confined to the stomach by a pyloric cuff than when it is allowed to enter the duodenum (6). To test the hypothesis that the reduced intake of water under normal drinking conditions is due to postgastric cellular hydration, we allowed rats to ingest pure water or 0.15 M NaCl with the pylorus open and with it closed. When the pylorus was open, rats ingested more NaCl than water. When it was closed, they drank an equal volume of each solution. With the cuff open, the rate of licking pure water began to decline within 3 min of the beginning of the test, an effect that did not occur when the cuff was closed or with NaCl under either test condition. These data support the hypothesis that the intake of water during the first 30 min of access to it following a period of water deprivation is inhibited by the hydration of cells located postgastrically.